<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  
</body>
<script>
  "use strict"
  const HOST={
    url: 'http://adun.com',
    port: 443
  }

  Object.freeze(HOST)
  
  //Uncaught TypeError: Cannot assign to read only property 'port' of object '#<Object>'
  // HOST.port=80

  console.log(HOST.port);
  
</script>
</html>